US20100138574A1 - Electronic apparatus and signal disconnection/connection method - Google Patents
Electronic apparatus and signal disconnection/connection method Download PDFInfo
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- US20100138574A1 US20100138574A1 US12/627,418 US62741809A US2010138574A1 US 20100138574 A1 US20100138574 A1 US 20100138574A1 US 62741809 A US62741809 A US 62741809A US 2010138574 A1 US2010138574 A1 US 2010138574A1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/40—Bus structure
- G06F13/4063—Device-to-bus coupling
- G06F13/4068—Electrical coupling
- G06F13/4081—Live connection to bus, e.g. hot-plugging
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D10/00—Energy efficient computing, e.g. low power processors, power management or thermal management
Definitions
- the present invention relates to an electronic apparatus and a signal disconnection/connection method.
- Multifunction products that have a copy function, a FAX function, a print function, a scanner function, and the like have been often used in recent years. It has been known that, in such multifunction products, the power for unnecessary functions is turned off during the energy-saving mode so that the power saving of the system is achieved.
- Japanese Patent Application Laid-open No. 2003-234073 discloses an image processing apparatus that includes an engine control unit including a scanner control unit and a plotter control unit, a controller control unit that controls the entire apparatus, and a power supply unit (PSU) that controls the power supply to these units and in which the controller control unit and the engine control unit are connected to each other via a PCI bus and a FAX board can be connected to the PCI bus as an option.
- an engine control unit including a scanner control unit and a plotter control unit, a controller control unit that controls the entire apparatus, and a power supply unit (PSU) that controls the power supply to these units and in which the controller control unit and the engine control unit are connected to each other via a PCI bus and a FAX board can be connected to the PCI bus as an option.
- PSU power supply unit
- the image processing apparatus has a stand-by mode, an engine-off mode, and a Suspend-To-RAM mode (STR) as energy-saving modes.
- the stand-by mode is a state in which the power of both the engine control unit and the controller control unit is turned on and is a mode that allows each operation (copy operation, scanner operation, and print operation) to be performed immediately.
- the engine-off mode is a state in which the power of the engine control unit is turned off and the power of the controller control unit is turned on and is a mode that allows communication such as a status notification to be performed between the image processing apparatus and an external device.
- the STR mode is a mode in which the power of the engine control unit is turned off and the power of the controller control unit is turned off except for some ICs thereof (the CPU is turned off).
- the FAX board connected to the PCI bus as an option detects a ringing signal from a phone line so that it can perform a FAX communication with a caller. At that time, a binary signal is generated from the received ringing signal and, if its frequency falls within a detection range of a ringing frequency, it is recognized as a ringing signal.
- a binary signal is generated in accordance with the rise/fall change of a ringing signal and, if the ringing signal is a sine wave, a clear binary signal is generated as shown in FIG. 13 and its frequency can be accurately measured.
- switching devices that output various ringing signals are available in the market, and some switching devices output a ringing signal with part of the waveform distorted, as shown in FIG. 14 .
- a binary signal is split in accordance with the rise-fall-rise change of the distorted part.
- the frequencies of two binary signals on the positive and negative sides are concurrently measured so that, even if the waveform on one side is split as shown in FIG. 14 , the frequency can be measured accurately by using the binary signal on the other side.
- the frequency cannot be measured accurately using any of the binary signals; therefore, such a case can be resolved only by expanding the frequency detection range (for example, the upper limit frequency is increased up to 100 Hz).
- the frequency detection range is expanded by software so that the frequency can be measured accurately even in the case shown in FIG. 15 .
- the detection frequency cannot be controlled by software and the detection frequency depends on the capability of a device that detects a ringing signal from the phone line. Therefore, there is a possibility that the frequency of the binary signal does not fall within the detection frequency range. In this case, there is a possibility that the ringing signal is not recognized and a FAX communication with the caller cannot be performed. To prevent this situation, the CPU of the FAX board cannot be turned off even during the STR mode.
- the controller control unit cannot shift to the STR mode.
- the power consumption is increased (from 2.1 Wh to 16.1 Wh) because the FAX board is connected.
- an electronic apparatus including: a first board that includes a first processor; a second board that is connected to the first board with a bus, the second board including a second processor; and a disconnecting/connecting unit that, when the first board is in a first state in which power of the first processor is turned off and the second board is in a second state in which power of the second processor is turned on, disconnects a signal supplied via the bus between the first board and the second board.
- a method of disconnecting and connecting a signal in an electronic apparatus that includes a first board that includes a first processor and a second board that is connected to the first board with a bus and that includes a second processor.
- the method includes disconnecting/connecting including, when the first board is in a first state in which power of the first processor is turned off and the second board is in a second state in which power of the second processor is turned on, disconnecting a signal supplied via the bus between the first board and the second board.
- FIG. 1 is a diagram illustrating boards that constitute an image forming apparatus according to a first embodiment of the present invention
- FIG. 2 is a diagram illustrating the outline of a circuit on a relay board
- FIG. 3 is a diagram illustrating a circuit configuration of bus switches
- FIG. 4 is a block diagram of a controller board
- FIG. 5 is a block diagram of a FAX controller board
- FIG. 6 is a sequence diagram showing a procedure for checking versions of the relay board, the FAX controller board, and software thereof according to a second embodiment of the present invention
- FIG. 7 is a diagram illustrating the circuit configuration to pull up a PCI bus according to a third embodiment of the present invention.
- FIG. 8 is a diagram illustrating a different circuit configuration to pull up the PCI bus according to the third embodiment.
- FIG. 9 is a circuit configuration diagram of a power generating unit according to a fourth embodiment of the present invention.
- FIG. 10 is a timing chart of the power rise timing of a controller board and the power rise timing of the FAX controller board;
- FIG. 11 is a diagram illustrating boards that constitute an image forming apparatus according to a fifth embodiment of the present invention.
- FIG. 12 is a block diagram of a FAX controller board according to the fifth embodiment.
- FIG. 13 is a diagram illustrating waveforms of binary signals if a ringing signal is a sine wave
- FIG. 14 is a diagram illustrating a state in which the waveform of the binary signal on the positive side is split due to the distortion of the ringing signal.
- FIG. 15 is a diagram illustrating a state in which the waveforms of the binary signals on both the positive and negative sides are split due to the distortion of the ringing signal.
- FIG. 1 is a diagram that illustrates boards that constitute an image forming apparatus that is an electronic apparatus according to a first embodiment of the present invention.
- the image forming apparatus includes a controller board 11 , a relay board 12 , a FAX controller board 13 , and an engine board 14 .
- the controller board 11 is a board on which a controller that controls the entire image forming apparatus is mounted
- the engine board 14 is a board on which a section that controls an image engine is mounted
- the FAX controller board 13 is an interface unit for a phone line in the image forming apparatus and a board on which a section that controls a FAX function is mounted.
- the relay board 12 is a board that connects the FAX controller board 13 , which is an option, to the controller board 11 to relay the transmission of signals via a PCI bus.
- the controller board 11 includes connectors 111 and 112 of the PCI bus so that the connector 111 is connected to a connector 141 of the engine board 14 and the connector 112 is connected to a connector 121 of the relay board 12 directly or via a cable.
- a connector 122 of the relay board 12 is connected to a connector 131 of the FAX controller board 13 directly or via a cable.
- FIG. 2 is a diagram that illustrates the outline of a circuit on the relay board 12 .
- the data path between the connector 121 and the connector 122 is connected via the PCI bus.
- a disconnecting/connecting unit 21 is arranged on the PCI bus.
- the disconnecting/connecting unit 21 is constituted by bus switches 21 a , 21 b .
- the bus switches 21 a , 21 b are turned on/off so that the data path between the connector 121 and the connector 122 can be disconnected/connected. Specifically, the bus switches are turned on/off so that signals flowing via the PCI bus between the connector 121 and the connector 122 are interrupted or passed through.
- the bus switches 21 a , 21 b are set to be on or off in accordance with the level (high/low) of an energy-saving signal 22 (the details will be described later) fed from the controller board 11 .
- FIG. 3 is a diagram that illustrates the circuit configuration of the bus switches 21 a , 21 b .
- the bus switches 21 a , 21 b are constituted by switches that include complementary metal oxide semiconductors (CMOS) 211 , 212 , which data signals are input to and output from, and buffers 213 , 214 , which feed on/off control signals to their gates in accordance with the energy-saving signal 22 .
- CMOS complementary metal oxide semiconductors
- the CMOSs 211 , 212 have low power consumption and, without degrading a propagation delay time, can connect/separate (disconnect) the bus.
- the bus is connected/separated (disconnected) by the CMOSs 211 , 212 so that the bus switches 21 a , 21 b perform the connection/separation (disconnection) in accordance with a control signal (the energy-saving signal 22 in the present embodiment), and if the control signal is set to a low (L) level, electrical continuity is established (on) and, if the control signal is set to a high (H) level, the electrical continuity is broken (off).
- a control signal the energy-saving signal 22 in the present embodiment
- the energy-saving signal 22 is set to L during the normal mode and the switches establish the electrical continuity, whereby data transaction between the controller board 11 and the FAX controller board 13 is allowed, and the energy-saving signal 22 is set to H during the energy-saving mode and the switches break the electrical continuity, whereby the data path between the controller board 11 and the FAX controller board 13 is disconnected. Because the energy-saving signal 22 is set to L upon the power-on of the image forming apparatus, a problem of impossible data communication does not occur upon the power-on.
- FIG. 4 is a block diagram that illustrates the configuration of the controller board 11 .
- the controller board 11 mainly includes a CPU 411 , ROMs 412 , 415 , a DRAM 413 , an I/O ASIC 414 , and an energy-saving control unit 416 .
- the I/O ASIC 414 is an ASIC that controls the PCI bus.
- the DRAM 413 functions as a working memory of a system program.
- the ROM 415 is a storage medium that stores therein an energy-saving control program to be executed by a CPU (not illustrated) built in the energy-saving control unit 416 .
- the energy-saving control unit 416 executes the energy-saving control program stored in the ROM 415 by using the built-in CPU, thereby perfuming the overall control during the energy-saving state.
- the energy-saving control unit 416 is a System on Chip (SoC).
- the image forming apparatus has, as the energy-saving modes if the FAX function is not provided as an option, the stand-by mode, the engine-off mode, and the STR mode.
- the stand-by mode is a mode in which, although the current is applied to the entire apparatus including the engine board 14 , an operation is not performed
- the engine-off mode is a mode in which, although the power of the engine board 14 is turned off, the current is applied to the controller board 11 .
- the STR mode is a mode in which the power of the engine board 14 is turned off and, with respect to the controller board 11 , the power of the CPU 411 is turned off and the current is applied to only some ICs, for example, an IC for network control, and the like, rather than the CPU.
- the energy-saving control unit 416 controls some ICs (including the bus switches 21 a , 21 b of the relay board 12 ) to which the current is applied if the power of the CPU is turned off during the STR mode.
- FIG. 5 is a block diagram that illustrates the configuration of the FAX controller board 13 .
- the FAX controller board 13 includes a CPU 31 , a RAM 32 , a modem 33 , a ROM 34 , and a data access arrangement (DAA) 35 .
- the CPU 31 , the RAM 32 , the modem 33 , and the ROM 34 are connected to one another via a bus.
- the DAA 35 is connected to the modem 33 and a phone line.
- the CPU 31 is connected to a PCI bus.
- the CPU 31 controls the FAX controller board 13 .
- the RAM 32 is a work area where various types of data and programs are temporarily stored when the CPU 31 is in operation.
- the modem 33 modulates/demodulates data (image data, various types of protocol data) with respect to the phone line.
- Various types of programs and fixed data to be executed by the CPU 31 are stored in the ROM 34 .
- the DAA 35 includes a ringing-signal detecting circuit that detects a ringing signal from the phone line and outputs it to the modem 33 .
- the operation of the ringing-signal detecting circuit is the same as that of the conventional apparatus shown in FIG. 13 .
- the control of the detection frequency cannot be performed by the software of the CPU 31 of the FAX controller board 13 and the detection frequency depends on the capability of the DAA 35 ; therefore, there is a possibility that the ringing signal is not recognized as a ringing signal and the FAX communication cannot be performed with a caller.
- the power of the CPU 31 of the FAX controller board 13 is not turned off during the STR mode, and the energy-saving signal 22 is set to the H level so that the bus switches 21 a , 21 b are turned off, whereby the PCI bus on the relay board 12 is disconnected.
- the PCI bus between the controller board 11 and the FAX controller board 13 is disconnected, the through current does not flow from the CPU 31 of the FAX controller board 13 into the controller board 11 .
- bus switches 21 a , 21 b are added to the PCI bus on the relay board 12 and the PCI bus is disconnected during the STR mode, whereby it is possible to put the controller board 11 into the energy-saving state and the FAX controller board 13 into the current-carrying state (normal state).
- the controller board 11 If the controller board 11 is to recover from the STR mode to the normal state in accordance with a FAX communication request from the outside, when the DAA 35 on the FAX controller board 13 detects a ringing signal, the CPU 31 generates a recovery signal 23 and sends the recovery signal 23 to the relay board 12 via the connector 131 , whereby the recovery signal 23 is sent to the connector 121 via a signal line that is different from the PCI bus on the relay board 12 and then the recovery signal 23 is sent to the controller board 11 .
- the energy-saving signal 22 is set to L so that the bus switches 21 a , 21 b establish electrical continuity, whereby the FAX controller board 13 and the controller board 11 are connected to each other via the PCI bus via the relay board 12 .
- the controller board 11 recovers to the normal state if the ringing signal from the phone line is detected, if a specified-time transmission is set in a timer within the FAX controller board 13 , the recovery signal 23 is output to the controller board 11 when the time is up so that the controller board 11 can recover to the normal state.
- the PCI bus is disconnected by the bus switches 21 a , 21 b on the relay board 12 during the STR mode even in a state in which the FAX controller board 13 is connected, which is an option that cannot shift to the energy-saving state, whereby the controller board 11 enters the energy-saving state and the FAX controller board 13 enters the current-carrying state (normal state). Therefore, even if the controller board 11 is in the energy-saving state, the FAX controller board 13 can detect a ringing signal from the outside and it is possible to prevent the through current from flowing into the controller board 11 .
- the power consumption is reduced from 16.1 Wh to 3.2 Wh, as measured by an actual apparatus, when the controller board 11 is in the energy-saving state.
- the power consumption is 9.1 Wh, as measured by the previously used apparatus.
- the controller board 11 , the relay board 12 , the FAX controller board 13 , and software thereof are all compatible with the STR mode; however, they can have different versions in reality.
- the controller board 11 is compatible with the STR mode and the relay board 12 or the FAX controller board 13 is not compatible with the STR mode
- the FAX controller board 13 detects a ringing signal in a state in which the controller board 11 has shifted to the STR mode
- the FAX controller board 13 cannot output the recovery signal 23 ; therefore, the controller board 11 cannot recover from the STR mode to the normal state and the FAX controller board 13 cannot start a FAX communication.
- the CPU of the controller board 11 has a function to check whether each of them has a version that is compatible with the STR mode. If the controller board 11 is not compatible with the STR mode, the controller board 11 does not shift to the STR mode; therefore, the above problem does not occur.
- the versions of the relay board 12 , the FAX controller board 13 , and the software thereof are checked by the process shown in FIG. 6 so that it is confirmed whether each of them is compatible with the STR mode.
- the controller board 11 requests the version of the software (Step S 1 ).
- the CPU 31 of the FAX controller board 13 has a function such that if the software is compatible with the STR mode, the FAX controller board 13 can respond with the version and, if the software is not compatible with the STR mode, the FAX controller board 13 does not respond.
- Step S 2 If the controller board 11 receives the version response from the FAX controller board 13 (Step S 2 ), the controller board 11 determines that the software with the version that allows the shift to the STR mode is implemented. Meanwhile, if the controller board 11 does not receive the version response from the FAX controller board 13 although a certain time has elapsed, the controller board 11 determines that the software of the FAX controller board 13 is software with a version that is not compatible with the STR mode. This process is performed so that it is determined whether the FAX controller board 13 and its software are compatible with the STR mode.
- the controller board 11 requests the FAX controller board 13 to output the recovery signal 23 as a trial in order to detect the version of the relay board 12 (Step S 3 ).
- the FAX controller board 13 outputs the recovery signal 23 (Step S 4 ).
- the controller board 11 determines that the relay board 12 is compatible with the STR mode, and conversely, if the controller board 11 cannot detect the recovery signal 23 , the controller board 11 determines that the relay board 12 is not compatible with the STR mode. After this determination, the controller board 11 requests the FAX controller board 13 to stop outputting the recovery signal 23 (Step S 5 ).
- the controller board 11 controls whether an optionally connected board is compatible with the STR mode or not, if the optionally connected board is not compatible with the STR mode, the controller board 11 does not enter the STR mode. Therefore, it is possible to prevent the case where the controller board 11 enters the STR mode without permission and cannot recover to the normal mode.
- the PCI bus has a negative logic, it is necessary to pull up the PCI bus with a pull-up voltage. Therefore, the PCI bus is pulled up on the controller board 11 .
- the PCI bus on the FAX controller board 13 connected as an option is also pulled up with a pull-up voltage. However, if the PCI bus is disconnected by the bus switches 21 a , 21 b during the STR mode, the PCI bus line cannot be pulled up due to its high impedance.
- a switch is arranged on the relay board 12 so that the PCI bus is also pulled up on the side of the FAX controller board 13 and the pull-up voltage does not rise on the side of the FAX controller board 13 from when the apparatus is started up to when it shifts to the STR mode.
- FIG. 7 is a diagram that illustrates the circuit configuration to pull up the PCI bus in the image forming apparatus according to the present embodiment.
- the PCI bus that connects the connector 112 to an ASIC 113 on the controller board 11 is pulled up to power Vdd 1 by a pull-up resistor 114 .
- the PCI bus (the PCI bus that connects the connector 122 to the bus switches 21 a , 21 b ) on the side of the FAX controller board 13 is pulled up to power Vdd 2 by a pull-up resistor 123 .
- a switch 124 constituted by a CMOS, or the like, is arranged in series to the pull-up resistor 123 and the pulling-up is turned on/off by the switch 124 .
- the switch 124 is turned off from when the apparatus is started up to when it shifts to the STR mode. Specifically, for example, when the energy-saving signal 22 is set to L, the switch is turned off and, if the energy-saving signal 22 is set to H, the switch is turned on.
- the pull-up means is also arranged on the relay board 12 so that, if the controller board 11 and the FAX controller board 13 are disconnected from each other due to the shift to the STR mode, the PCI bus on the FAX controller board 13 can be pulled up. Moreover, the timing of the pulling-up of the PCI bus on the relay board 12 is controlled so that it is possible to prevent the through current flowing into the controller board 11 and the voltage dividing.
- the rise timing of the CPU 31 of the FAX controller board 13 is faster than the rise timing of the pull-up voltage, the power is first applied to an I/O port of the PCI bus of the CPU 31 , whereby the through current flows into the controller board 11 . Therefore, the rise timing of the power of the FAX controller board 13 needs to be later than the rise timing of the pull-up voltage. If the controller board 11 is in the normal state, the rise can be controlled by using a control signal from the controller board 11 ; however, if the controller board 11 shifts to the STR mode, the control signal from the controller board 11 falls, whereby the power voltage of the FAX controller board 13 falls.
- the rise time is controlled with hardware by using a Field Effect Transistor (FET) and the RC time constant on the relay board 12 .
- FIG. 9 is a circuit configuration diagram of a power generating unit 125 that controls such a rise time.
- the power generating unit 125 is a circuit that generates the power (Vdd 2 ) to be supplied to the FAX controller board 13 and is arranged on the relay board 12 .
- An FET 126 has a function as a switch that generates the Vdd 2 .
- the power rise timing of the FAX controller board 13 is controlled by using the FET 126 and the RC time constant of a resistance R of a resistor 127 and a capacitance C of a capacitor 128 .
- FIG. 10 is a timing chart that illustrates the power rise timing of the controller board 11 and the power rise timing of the FAX controller board 13 .
- the Vdd 1 is the power voltage of the controller board 11
- the reference numeral 902 indicates the waveform of the power rise of the controller board 11 .
- the Vdd 2 is the power voltage of the FAX controller board 13
- the reference numeral 903 indicates the waveform of the power rise of the FAX controller board 13 .
- the power generating unit 125 of the relay board 12 causes the power rise timing of the FAX controller board 13 to be delayed by a time difference 901 relative to the power rise timing of the controller board 11 .
- the power rise is controlled by, rather than the control signal from the controller board 11 , the hardware on the relay board 12 such that the power rise occurs later than the rise of the pull-up voltage, whereby even if the controller board 11 enters the energy-saving state, it is possible to cause the power voltage of the FAX controller board 13 to keep rising.
- relay board 12 has the function to connect/disconnect the PCI bus in the first to fourth embodiments
- a FAX controller board has the function to connect/disconnect the PCI bus in a fifth embodiment of the present invention.
- FIG. 11 is a diagram that illustrates boards that constitute an image forming apparatus that is an electronic apparatus according to the fifth embodiment.
- the image forming apparatus includes the controller board 11 , a FAX controller board 1113 , and the engine board 14 , and the FAX controller board 1113 is connected to the controller board 11 without involving a relay board.
- the functions and configuration of the engine board 14 and the controller board 11 are the same as those in the first to fourth embodiments.
- FIG. 12 is a block diagram that illustrates the configuration of the FAX controller board according to the fifth embodiment.
- the FAX controller board 1113 according to the present embodiment includes the CPU 31 , the RAM 32 , the modem 33 , the ROM 34 , the DAA 35 , and the disconnecting/connecting unit 21 .
- the functions of the CPU 31 , the RAM 32 , the modem 33 , the ROM 34 , and the DAA 35 are the same as those in the first to fourth embodiments.
- the disconnecting/connecting unit 21 has the same functions and configuration as those of the disconnecting/connecting unit 21 arranged on the relay board according to the first embodiment and includes the bus switches 21 a , 21 b .
- the bus switches 21 a , 21 b are turned on/off so that the data path between the CPU 31 and the connector 131 can be disconnected/connected.
- the configuration of the bus switches 21 a , 21 b is the same as that described in the first embodiment with reference to FIGS. 2 and 3 . Specifically, the bus switches are turned on/off so that signals flowing via the PCI bus between the CPU 31 and the connector 131 are interrupted or passed through.
- the bus switches 21 a , 21 b establish electrical continuity (on) and, if it is set to the high (H) level, breaks the electrical continuity (off).
- the energy-saving signal 22 is set to L during the normal mode and the switches establish the electrical continuity, whereby data transaction between the controller board 11 and the FAX controller board 1113 is allowed, and the energy-saving signal 22 is set to H during the energy-saving mode and the switches break the electrical continuity, whereby the data path between the controller board 11 and the FAX controller board 1113 is disconnected.
- the same function as the relay board 12 according to the first embodiment is achieved by the disconnecting/connecting unit 21 on the FAX controller board 1113 .
- the FAX controller board 1113 has the function to disconnect/connect the PCI bus, the same advantage as the first embodiment can be produced, and the relay board is not necessary, whereby the configuration can be simplified.
- PCI bus is used as a bus
- present invention is not limited to this, and other buses such as a local bus can be used.
- the through current does not flow from the second board to the first board; therefore, an advantage can be produced such that damage to the first board due to the through current flowing from the second board to the first board is prevented while the energy-saving of an apparatus is achieved.
Abstract
Description
- The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2008-306439 filed in Japan on Dec. 1, 2008 and Japanese Patent Application No. 2009-256:375 filed in Japan on Nov. 9, 2009.
- 1. Field of the Invention
- The present invention relates to an electronic apparatus and a signal disconnection/connection method.
- 2. Description of the Related Art
- Multifunction products that have a copy function, a FAX function, a print function, a scanner function, and the like have been often used in recent years. It has been known that, in such multifunction products, the power for unnecessary functions is turned off during the energy-saving mode so that the power saving of the system is achieved.
- For example, Japanese Patent Application Laid-open No. 2003-234073 discloses an image processing apparatus that includes an engine control unit including a scanner control unit and a plotter control unit, a controller control unit that controls the entire apparatus, and a power supply unit (PSU) that controls the power supply to these units and in which the controller control unit and the engine control unit are connected to each other via a PCI bus and a FAX board can be connected to the PCI bus as an option.
- The image processing apparatus has a stand-by mode, an engine-off mode, and a Suspend-To-RAM mode (STR) as energy-saving modes. The stand-by mode is a state in which the power of both the engine control unit and the controller control unit is turned on and is a mode that allows each operation (copy operation, scanner operation, and print operation) to be performed immediately. The engine-off mode is a state in which the power of the engine control unit is turned off and the power of the controller control unit is turned on and is a mode that allows communication such as a status notification to be performed between the image processing apparatus and an external device. The STR mode is a mode in which the power of the engine control unit is turned off and the power of the controller control unit is turned off except for some ICs thereof (the CPU is turned off).
- In the image processing apparatus, the FAX board connected to the PCI bus as an option detects a ringing signal from a phone line so that it can perform a FAX communication with a caller. At that time, a binary signal is generated from the received ringing signal and, if its frequency falls within a detection range of a ringing frequency, it is recognized as a ringing signal.
- A binary signal is generated in accordance with the rise/fall change of a ringing signal and, if the ringing signal is a sine wave, a clear binary signal is generated as shown in
FIG. 13 and its frequency can be accurately measured. However, switching devices that output various ringing signals are available in the market, and some switching devices output a ringing signal with part of the waveform distorted, as shown inFIG. 14 . - When the ringing signal output from the switching device is detected, a binary signal is split in accordance with the rise-fall-rise change of the distorted part. The frequencies of two binary signals on the positive and negative sides are concurrently measured so that, even if the waveform on one side is split as shown in
FIG. 14 , the frequency can be measured accurately by using the binary signal on the other side. However, for example, if both of the two binary signals are split as shown inFIG. 15 , the frequency cannot be measured accurately using any of the binary signals; therefore, such a case can be resolved only by expanding the frequency detection range (for example, the upper limit frequency is increased up to 100 Hz). - If the CPU of the FAX board is turned on, the frequency detection range is expanded by software so that the frequency can be measured accurately even in the case shown in
FIG. 15 . However, if the CPU of the FAX board is turned off during the STR mode, the detection frequency cannot be controlled by software and the detection frequency depends on the capability of a device that detects a ringing signal from the phone line. Therefore, there is a possibility that the frequency of the binary signal does not fall within the detection frequency range. In this case, there is a possibility that the ringing signal is not recognized and a FAX communication with the caller cannot be performed. To prevent this situation, the CPU of the FAX board cannot be turned off even during the STR mode. - However, if the power of the FAX board is turned on during the STR mode, because the FAX board is connected to the controller control unit via the PCI bus, the current passes through the PCI bus and flows into the controller control unit from the FAX board, which can significantly affect the IC of the controller control unit.
- Therefore, if the FAX board is connected, the controller control unit cannot shift to the STR mode. Thus, there is a problem in that the power consumption is increased (from 2.1 Wh to 16.1 Wh) because the FAX board is connected.
- It is an object of the present invention to at least partially solve the problems in the conventional technology.
- According to one aspect of the present invention, there is provided an electronic apparatus including: a first board that includes a first processor; a second board that is connected to the first board with a bus, the second board including a second processor; and a disconnecting/connecting unit that, when the first board is in a first state in which power of the first processor is turned off and the second board is in a second state in which power of the second processor is turned on, disconnects a signal supplied via the bus between the first board and the second board.
- Furthermore, according to another aspect of the present invention, there is provided a method of disconnecting and connecting a signal in an electronic apparatus that includes a first board that includes a first processor and a second board that is connected to the first board with a bus and that includes a second processor. The method includes disconnecting/connecting including, when the first board is in a first state in which power of the first processor is turned off and the second board is in a second state in which power of the second processor is turned on, disconnecting a signal supplied via the bus between the first board and the second board.
- The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
-
FIG. 1 is a diagram illustrating boards that constitute an image forming apparatus according to a first embodiment of the present invention; -
FIG. 2 is a diagram illustrating the outline of a circuit on a relay board; -
FIG. 3 is a diagram illustrating a circuit configuration of bus switches; -
FIG. 4 is a block diagram of a controller board; -
FIG. 5 is a block diagram of a FAX controller board; -
FIG. 6 is a sequence diagram showing a procedure for checking versions of the relay board, the FAX controller board, and software thereof according to a second embodiment of the present invention; -
FIG. 7 is a diagram illustrating the circuit configuration to pull up a PCI bus according to a third embodiment of the present invention; -
FIG. 8 is a diagram illustrating a different circuit configuration to pull up the PCI bus according to the third embodiment; -
FIG. 9 is a circuit configuration diagram of a power generating unit according to a fourth embodiment of the present invention; -
FIG. 10 is a timing chart of the power rise timing of a controller board and the power rise timing of the FAX controller board; -
FIG. 11 is a diagram illustrating boards that constitute an image forming apparatus according to a fifth embodiment of the present invention; -
FIG. 12 is a block diagram of a FAX controller board according to the fifth embodiment; -
FIG. 13 is a diagram illustrating waveforms of binary signals if a ringing signal is a sine wave; -
FIG. 14 is a diagram illustrating a state in which the waveform of the binary signal on the positive side is split due to the distortion of the ringing signal; and -
FIG. 15 is a diagram illustrating a state in which the waveforms of the binary signals on both the positive and negative sides are split due to the distortion of the ringing signal. - Exemplary embodiments of an electronic apparatus and a signal disconnection/connection method according to the present invention are explained in detail below with reference to the accompanying drawings.
-
FIG. 1 is a diagram that illustrates boards that constitute an image forming apparatus that is an electronic apparatus according to a first embodiment of the present invention. The image forming apparatus includes acontroller board 11, arelay board 12, aFAX controller board 13, and anengine board 14. - The
controller board 11 is a board on which a controller that controls the entire image forming apparatus is mounted, theengine board 14 is a board on which a section that controls an image engine is mounted, and theFAX controller board 13 is an interface unit for a phone line in the image forming apparatus and a board on which a section that controls a FAX function is mounted. Therelay board 12 is a board that connects theFAX controller board 13, which is an option, to thecontroller board 11 to relay the transmission of signals via a PCI bus. - The
controller board 11 includesconnectors connector 111 is connected to aconnector 141 of theengine board 14 and theconnector 112 is connected to aconnector 121 of therelay board 12 directly or via a cable. Aconnector 122 of therelay board 12 is connected to aconnector 131 of theFAX controller board 13 directly or via a cable. -
FIG. 2 is a diagram that illustrates the outline of a circuit on therelay board 12. The data path between theconnector 121 and theconnector 122 is connected via the PCI bus. Furthermore, a disconnecting/connectingunit 21 is arranged on the PCI bus. The disconnecting/connectingunit 21 is constituted bybus switches connector 121 and theconnector 122 can be disconnected/connected. Specifically, the bus switches are turned on/off so that signals flowing via the PCI bus between theconnector 121 and theconnector 122 are interrupted or passed through. The bus switches 21 a, 21 b are set to be on or off in accordance with the level (high/low) of an energy-saving signal 22 (the details will be described later) fed from thecontroller board 11. -
FIG. 3 is a diagram that illustrates the circuit configuration of the bus switches 21 a, 21 b. The bus switches 21 a, 21 b are constituted by switches that include complementary metal oxide semiconductors (CMOS) 211, 212, which data signals are input to and output from, and buffers 213, 214, which feed on/off control signals to their gates in accordance with the energy-savingsignal 22. - The
CMOSs CMOSs signal 22 in the present embodiment), and if the control signal is set to a low (L) level, electrical continuity is established (on) and, if the control signal is set to a high (H) level, the electrical continuity is broken (off). - Because of the use of the bus switches 21 a, 21 b with such a structure, the energy-saving
signal 22 is set to L during the normal mode and the switches establish the electrical continuity, whereby data transaction between thecontroller board 11 and theFAX controller board 13 is allowed, and the energy-savingsignal 22 is set to H during the energy-saving mode and the switches break the electrical continuity, whereby the data path between thecontroller board 11 and theFAX controller board 13 is disconnected. Because the energy-savingsignal 22 is set to L upon the power-on of the image forming apparatus, a problem of impossible data communication does not occur upon the power-on. -
FIG. 4 is a block diagram that illustrates the configuration of thecontroller board 11. As shown inFIG. 4 , thecontroller board 11 mainly includes aCPU 411,ROMs DRAM 413, an I/O ASIC 414, and an energy-savingcontrol unit 416. - The I/
O ASIC 414 is an ASIC that controls the PCI bus. TheDRAM 413 functions as a working memory of a system program. TheROM 415 is a storage medium that stores therein an energy-saving control program to be executed by a CPU (not illustrated) built in the energy-savingcontrol unit 416. The energy-savingcontrol unit 416 executes the energy-saving control program stored in theROM 415 by using the built-in CPU, thereby perfuming the overall control during the energy-saving state. Specifically, the energy-savingcontrol unit 416 is a System on Chip (SoC). - The image forming apparatus according to the present embodiment has, as the energy-saving modes if the FAX function is not provided as an option, the stand-by mode, the engine-off mode, and the STR mode. The stand-by mode is a mode in which, although the current is applied to the entire apparatus including the
engine board 14, an operation is not performed, and the engine-off mode is a mode in which, although the power of theengine board 14 is turned off, the current is applied to thecontroller board 11. Moreover, the STR mode is a mode in which the power of theengine board 14 is turned off and, with respect to thecontroller board 11, the power of theCPU 411 is turned off and the current is applied to only some ICs, for example, an IC for network control, and the like, rather than the CPU. The energy-savingcontrol unit 416 controls some ICs (including the bus switches 21 a, 21 b of the relay board 12) to which the current is applied if the power of the CPU is turned off during the STR mode. -
FIG. 5 is a block diagram that illustrates the configuration of theFAX controller board 13. TheFAX controller board 13 includes aCPU 31, aRAM 32, amodem 33, aROM 34, and a data access arrangement (DAA) 35. TheCPU 31, theRAM 32, themodem 33, and theROM 34 are connected to one another via a bus. TheDAA 35 is connected to themodem 33 and a phone line. Moreover, theCPU 31 is connected to a PCI bus. - The
CPU 31 controls theFAX controller board 13. TheRAM 32 is a work area where various types of data and programs are temporarily stored when theCPU 31 is in operation. Themodem 33 modulates/demodulates data (image data, various types of protocol data) with respect to the phone line. Various types of programs and fixed data to be executed by theCPU 31 are stored in theROM 34. TheDAA 35 includes a ringing-signal detecting circuit that detects a ringing signal from the phone line and outputs it to themodem 33. The operation of the ringing-signal detecting circuit is the same as that of the conventional apparatus shown inFIG. 13 . - As shown in
FIG. 1 , if the power of theCPU 31 of theFAX controller board 13 is turned off when the apparatus enters the STR mode in a state in which theFAX controller board 13 is connected so that the power of the CPU of thecontroller board 11 is turned off, the control of the detection frequency cannot be performed by the software of theCPU 31 of theFAX controller board 13 and the detection frequency depends on the capability of theDAA 35; therefore, there is a possibility that the ringing signal is not recognized as a ringing signal and the FAX communication cannot be performed with a caller. - Therefore, in the present embodiment, the power of the
CPU 31 of theFAX controller board 13 is not turned off during the STR mode, and the energy-savingsignal 22 is set to the H level so that the bus switches 21 a, 21 b are turned off, whereby the PCI bus on therelay board 12 is disconnected. As a result, because the PCI bus between thecontroller board 11 and theFAX controller board 13 is disconnected, the through current does not flow from theCPU 31 of theFAX controller board 13 into thecontroller board 11. - Thus, the bus switches 21 a, 21 b are added to the PCI bus on the
relay board 12 and the PCI bus is disconnected during the STR mode, whereby it is possible to put thecontroller board 11 into the energy-saving state and theFAX controller board 13 into the current-carrying state (normal state). - If the
controller board 11 is to recover from the STR mode to the normal state in accordance with a FAX communication request from the outside, when theDAA 35 on theFAX controller board 13 detects a ringing signal, theCPU 31 generates arecovery signal 23 and sends therecovery signal 23 to therelay board 12 via theconnector 131, whereby therecovery signal 23 is sent to theconnector 121 via a signal line that is different from the PCI bus on therelay board 12 and then therecovery signal 23 is sent to thecontroller board 11. When thecontroller board 11 recovers to the normal state, the energy-savingsignal 22 is set to L so that the bus switches 21 a, 21 b establish electrical continuity, whereby theFAX controller board 13 and thecontroller board 11 are connected to each other via the PCI bus via therelay board 12. - Although the case is explained above where the
controller board 11 recovers to the normal state if the ringing signal from the phone line is detected, if a specified-time transmission is set in a timer within theFAX controller board 13, therecovery signal 23 is output to thecontroller board 11 when the time is up so that thecontroller board 11 can recover to the normal state. - Thus, with the image forming apparatus according to the first embodiment, the PCI bus is disconnected by the bus switches 21 a, 21 b on the
relay board 12 during the STR mode even in a state in which theFAX controller board 13 is connected, which is an option that cannot shift to the energy-saving state, whereby thecontroller board 11 enters the energy-saving state and theFAX controller board 13 enters the current-carrying state (normal state). Therefore, even if thecontroller board 11 is in the energy-saving state, theFAX controller board 13 can detect a ringing signal from the outside and it is possible to prevent the through current from flowing into thecontroller board 11. Specifically, the power consumption is reduced from 16.1 Wh to 3.2 Wh, as measured by an actual apparatus, when thecontroller board 11 is in the energy-saving state. The power consumption is 9.1 Wh, as measured by the previously used apparatus. Conventionally, it is not assumed that an option board that cannot shift to the energy-saving state is connected; however, such an option board can be connected. Furthermore, it is possible to recover thecontroller board 11 to the normal state by a recovery factor of theFAX controller board 13. - There is no problem if the
controller board 11, therelay board 12, theFAX controller board 13, and software thereof are all compatible with the STR mode; however, they can have different versions in reality. For example, in the case where thecontroller board 11 is compatible with the STR mode and therelay board 12 or theFAX controller board 13 is not compatible with the STR mode, if theFAX controller board 13 detects a ringing signal in a state in which thecontroller board 11 has shifted to the STR mode, theFAX controller board 13 cannot output therecovery signal 23; therefore, thecontroller board 11 cannot recover from the STR mode to the normal state and theFAX controller board 13 cannot start a FAX communication. - Therefore, in the present embodiment, the CPU of the
controller board 11 has a function to check whether each of them has a version that is compatible with the STR mode. If thecontroller board 11 is not compatible with the STR mode, thecontroller board 11 does not shift to the STR mode; therefore, the above problem does not occur. The versions of therelay board 12, theFAX controller board 13, and the software thereof are checked by the process shown inFIG. 6 so that it is confirmed whether each of them is compatible with the STR mode. - First, the
controller board 11 requests the version of the software (Step S1). At that time, theCPU 31 of theFAX controller board 13 has a function such that if the software is compatible with the STR mode, theFAX controller board 13 can respond with the version and, if the software is not compatible with the STR mode, theFAX controller board 13 does not respond. - If the
controller board 11 receives the version response from the FAX controller board 13 (Step S2), thecontroller board 11 determines that the software with the version that allows the shift to the STR mode is implemented. Meanwhile, if thecontroller board 11 does not receive the version response from theFAX controller board 13 although a certain time has elapsed, thecontroller board 11 determines that the software of theFAX controller board 13 is software with a version that is not compatible with the STR mode. This process is performed so that it is determined whether theFAX controller board 13 and its software are compatible with the STR mode. - Next, the
controller board 11 requests theFAX controller board 13 to output therecovery signal 23 as a trial in order to detect the version of the relay board 12 (Step S3). - The
FAX controller board 13 outputs the recovery signal 23 (Step S4). At that time, if therelay board 12 is not compatible with the STR mode, that is, if a signal line for recovery signals is not present, therecovery signal 23 is not transmitted to thecontroller board 11; therefore, thecontroller board 11 cannot detect therecovery signal 23. Therefore, if thecontroller board 11 can detect therecovery signal 23 within a certain time, thecontroller board 11 determines that therelay board 12 is compatible with the STR mode, and conversely, if thecontroller board 11 cannot detect therecovery signal 23, thecontroller board 11 determines that therelay board 12 is not compatible with the STR mode. After this determination, thecontroller board 11 requests theFAX controller board 13 to stop outputting the recovery signal 23 (Step S5). - With an image forming apparatus according to a second embodiment of the present invention, because the
controller board 11 controls whether an optionally connected board is compatible with the STR mode or not, if the optionally connected board is not compatible with the STR mode, thecontroller board 11 does not enter the STR mode. Therefore, it is possible to prevent the case where thecontroller board 11 enters the STR mode without permission and cannot recover to the normal mode. - Because the PCI bus has a negative logic, it is necessary to pull up the PCI bus with a pull-up voltage. Therefore, the PCI bus is pulled up on the
controller board 11. In the first embodiment, the PCI bus on theFAX controller board 13 connected as an option is also pulled up with a pull-up voltage. However, if the PCI bus is disconnected by the bus switches 21 a, 21 b during the STR mode, the PCI bus line cannot be pulled up due to its high impedance. - Therefore, it is necessary to pull up the PCI bus on the side of the
FAX controller board 13. However, if the PCI bus is also pulled up on the side of theFAX controller board 13, the PCI bus is pulled up on two positions during the normal mode, which causes voltage dividing. Furthermore, if the PCI bus is pulled up on the side of theFAX controller board 13 before thecontroller board 11 is started up upon the start-up of the apparatus, the through current flows into the IC of thecontroller board 11. - Therefore, in the image forming apparatus according to the present embodiment, a switch is arranged on the
relay board 12 so that the PCI bus is also pulled up on the side of theFAX controller board 13 and the pull-up voltage does not rise on the side of theFAX controller board 13 from when the apparatus is started up to when it shifts to the STR mode. -
FIG. 7 is a diagram that illustrates the circuit configuration to pull up the PCI bus in the image forming apparatus according to the present embodiment. As shown in the figure, the PCI bus that connects theconnector 112 to anASIC 113 on thecontroller board 11 is pulled up to power Vdd1 by a pull-upresistor 114. Moreover, on therelay board 12, with respect to the disconnecting/connecting unit 21 (the bus switches 21 a, 21 b), the PCI bus (the PCI bus that connects theconnector 122 to the bus switches 21 a, 21 b) on the side of theFAX controller board 13 is pulled up to power Vdd2 by a pull-upresistor 123. - Furthermore, as shown in
FIG. 8 , it is possible to configure such that aswitch 124 constituted by a CMOS, or the like, is arranged in series to the pull-upresistor 123 and the pulling-up is turned on/off by theswitch 124. In this case, theswitch 124 is turned off from when the apparatus is started up to when it shifts to the STR mode. Specifically, for example, when the energy-savingsignal 22 is set to L, the switch is turned off and, if the energy-savingsignal 22 is set to H, the switch is turned on. - With such a configuration, it is possible that the pull-up voltage on the side of the
FAX controller board 13 is prevented from rising from when the apparatus is started up to when it shifts to the STR mode, whereby the through current is prevented from flowing into the IC of thecontroller board 11, and the PCI bus on theFAX controller board 13 is pulled up by the pull-upresistor 123 on therelay board 12 during the STR mode. - According to a third embodiment of the present invention, the pull-up means is also arranged on the
relay board 12 so that, if thecontroller board 11 and theFAX controller board 13 are disconnected from each other due to the shift to the STR mode, the PCI bus on theFAX controller board 13 can be pulled up. Moreover, the timing of the pulling-up of the PCI bus on therelay board 12 is controlled so that it is possible to prevent the through current flowing into thecontroller board 11 and the voltage dividing. - If the rise timing of the
CPU 31 of theFAX controller board 13 is faster than the rise timing of the pull-up voltage, the power is first applied to an I/O port of the PCI bus of theCPU 31, whereby the through current flows into thecontroller board 11. Therefore, the rise timing of the power of theFAX controller board 13 needs to be later than the rise timing of the pull-up voltage. If thecontroller board 11 is in the normal state, the rise can be controlled by using a control signal from thecontroller board 11; however, if thecontroller board 11 shifts to the STR mode, the control signal from thecontroller board 11 falls, whereby the power voltage of theFAX controller board 13 falls. - According to a fourth embodiment of the present invention, the rise time is controlled with hardware by using a Field Effect Transistor (FET) and the RC time constant on the
relay board 12.FIG. 9 is a circuit configuration diagram of apower generating unit 125 that controls such a rise time. Thepower generating unit 125 is a circuit that generates the power (Vdd2) to be supplied to theFAX controller board 13 and is arranged on therelay board 12. AnFET 126 has a function as a switch that generates the Vdd2. In thepower generating unit 125 according to the present embodiment, the power rise timing of theFAX controller board 13 is controlled by using theFET 126 and the RC time constant of a resistance R of aresistor 127 and a capacitance C of acapacitor 128. -
FIG. 10 is a timing chart that illustrates the power rise timing of thecontroller board 11 and the power rise timing of theFAX controller board 13. As shown inFIG. 10 , the Vdd1 is the power voltage of thecontroller board 11, and thereference numeral 902 indicates the waveform of the power rise of thecontroller board 11. Furthermore, the Vdd2 is the power voltage of theFAX controller board 13, and thereference numeral 903 indicates the waveform of the power rise of theFAX controller board 13. As shown inFIG. 10 , thepower generating unit 125 of therelay board 12 causes the power rise timing of theFAX controller board 13 to be delayed by atime difference 901 relative to the power rise timing of thecontroller board 11. - Thus, in the present embodiment, the power rise is controlled by, rather than the control signal from the
controller board 11, the hardware on therelay board 12 such that the power rise occurs later than the rise of the pull-up voltage, whereby even if thecontroller board 11 enters the energy-saving state, it is possible to cause the power voltage of theFAX controller board 13 to keep rising. - Although the
relay board 12 has the function to connect/disconnect the PCI bus in the first to fourth embodiments, a FAX controller board has the function to connect/disconnect the PCI bus in a fifth embodiment of the present invention. -
FIG. 11 is a diagram that illustrates boards that constitute an image forming apparatus that is an electronic apparatus according to the fifth embodiment. The image forming apparatus includes thecontroller board 11, aFAX controller board 1113, and theengine board 14, and theFAX controller board 1113 is connected to thecontroller board 11 without involving a relay board. The functions and configuration of theengine board 14 and thecontroller board 11 are the same as those in the first to fourth embodiments. -
FIG. 12 is a block diagram that illustrates the configuration of the FAX controller board according to the fifth embodiment. As shown inFIG. 12 , theFAX controller board 1113 according to the present embodiment includes theCPU 31, theRAM 32, themodem 33, theROM 34, theDAA 35, and the disconnecting/connectingunit 21. The functions of theCPU 31, theRAM 32, themodem 33, theROM 34, and theDAA 35 are the same as those in the first to fourth embodiments. - The disconnecting/connecting
unit 21 has the same functions and configuration as those of the disconnecting/connectingunit 21 arranged on the relay board according to the first embodiment and includes the bus switches 21 a, 21 b. The bus switches 21 a, 21 b are turned on/off so that the data path between theCPU 31 and theconnector 131 can be disconnected/connected. The configuration of the bus switches 21 a, 21 b is the same as that described in the first embodiment with reference toFIGS. 2 and 3 . Specifically, the bus switches are turned on/off so that signals flowing via the PCI bus between theCPU 31 and theconnector 131 are interrupted or passed through. Concretely, if the energy-savingsignal 22 fed from thecontroller board 11 is set to the low (L) level, the bus switches 21 a, 21 b establish electrical continuity (on) and, if it is set to the high (H) level, breaks the electrical continuity (off). - Because of the use of the bus switches 21 a, 21 b, the energy-saving
signal 22 is set to L during the normal mode and the switches establish the electrical continuity, whereby data transaction between thecontroller board 11 and theFAX controller board 1113 is allowed, and the energy-savingsignal 22 is set to H during the energy-saving mode and the switches break the electrical continuity, whereby the data path between thecontroller board 11 and theFAX controller board 1113 is disconnected. Thus, the same function as therelay board 12 according to the first embodiment is achieved by the disconnecting/connectingunit 21 on theFAX controller board 1113. - As described above, in the present embodiment, because the
FAX controller board 1113 has the function to disconnect/connect the PCI bus, the same advantage as the first embodiment can be produced, and the relay board is not necessary, whereby the configuration can be simplified. - Although the example where the PCI bus is used as a bus is explained in the above embodiments, the present invention is not limited to this, and other buses such as a local bus can be used.
- According to an aspect of the present invention, when a first board is in the energy-saving state and a second board is in the normal state, the through current does not flow from the second board to the first board; therefore, an advantage can be produced such that damage to the first board due to the through current flowing from the second board to the first board is prevented while the energy-saving of an apparatus is achieved.
- Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
Claims (10)
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JP2009256375A JP2010157995A (en) | 2008-12-01 | 2009-11-09 | Electronic apparatus and signal disconnection/connection method |
JP2009-256375 | 2009-11-09 |
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US9558137B2 (en) * | 2012-12-06 | 2017-01-31 | Hon Hai Precision Industry Co., Ltd. | Card control device and control card of computer system having card control device |
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US20140281220A1 (en) * | 2013-03-18 | 2014-09-18 | Fujitsu Limited | Information processing system, and control method |
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